Hi everybody,

According to this, unigine provides

64-bit coordinates precision: real-world scale of virtual scenes as large as the solar system

Do some people have some more information about what they are using internally ? Mainly, I would like to know if they do it all in 64 bits (meaning that vertex positions are sent to the GPUs in 64 bits precision), or do they do any tricks (ie 64-bits precision at editing time, then do some split-tricks, then at runtime, the GPU operates with 32 bits position) ?

When reading further their website, it seems we can even see more farther than on usual engines and close and far things at the same time (see this page), letting me believe they might be using 64 bits floats without any tricks to send them as 32 bits to the GPU...

If anyone has some documents about how they manage this internally, please let me be aware of them.

Thanks.

It's certainly some sort of virtual 64bit precision, two 32bit depth buffers or some such thing. A single 32bit buffer wouldn't give any benefit, it's already common to flip it for more precision over a range. And native 64bit is sloooooow even on most "professional" cards, let alone average consumer ones. Star Citizen does virtual 64bit, though I never learned the details I'd bet it's pretty much the same.

Thanks a lot for the replies. They are relevant.

So to recap, and to check if I understood correctly:

• 64-bits projection/modelview CPU-side matrices sent as a single 32-bits mvp to the GPU
• Most probably usual 24-bits depth buffer
• Logarithmic depth to allow tweak if necessary
• And probably 64-bits position precision on CPU-side

Most probably usual 24-bits depth buffer

24bit integer depth buffers are unusual these days. 32bit float is normal. Most GPU's will store a 24-bit depth-stencil as a 32bpp depth texture (with 8bpp wasted), plus a completely separate 8bpp stencil buffer -- so there's no benefit over using a float32 depth format.

Thank you also for this. So it seems that offscreen rendering (threw FBOs) is really the way to do things nowadays.